1. Field of the Invention
The invention pertains to a delay device for a frequency signal and, notably, to a delay line device for microwave signals as well as to a system applying this device.
More particularly, the invention concerns an acoustic delay line device that is continuously variable by electronic control.
The main applications thereof are in the processing of wide-band radar signals for the control of the scanning of an electronic antenna.
For this, control is achieved by acting on the delays of the different elements of the antenna.
2. Description of the Prior Art
In prior art devices, these delays are generated by coaxial lines or wave guides (such as symmetrical strip lines) associated with switch-over devices. However, devices such as these are bulky and occupy much space.
The French patent application No. 87 05267 describes a system enabling the generation of delays for microwave signals using optical means. These signals make it possible to produce a microwave signal by the beating of two light waves. There are several light paths available, each making it possible to control an antenna element. The different paths have different lengths. This enables the generation of the relative delays in the control of the different antenna elements.
However, a system of this kind does not enable the generation of continuously variable delays.
The invention concerns a device that can be used to vary the delay of a microwave signal in a continuously variable manner.